Cabin heat box options

[Zzz]

I'm kind of in a phase of hanging stuff on my firewall mockup (big sheet of plexi.) One area I am focused on is lower firewall center, where I've got some brake line routing, parking brake, and where I expect to pass cabin heat in.

What is everyone using for off-the-shelf cabin heat valves/boxes? Any experience with these ones from Vans? https://www.vansaircraft.com/cgi-bin...t-selector-box

How about this one from Spruce? https://www.aircraftspruce.com/catal...heaterbox3.php

I'd like to be able to plumb in a defroster too. Does that require another box? A tee on the cabin side of the firewall and some scat hose run up to the glareshield?

Curious to see what everyone else is doing.

Thanks,
Z

[N942VT]

I used the ACS standard homebuilders box which worked well, a company called Robin's Wings makes another good one, used their heat muffs. You won't need a separate box for defrost, these put out allot of volume if they're set up right, just a diverter valve for the defrost. In 300 hours I've never needed defrost, not sure if you will.

[Zzz]

Dave, this diverter valve is mounted to the cabin side of the firewall to mate with the box? I've had some cold wet dewey mornings here in the NW where I would have loved a defroster that worked well.

[N942VT]

Right, that's how I've seen most defrosters set up. I've also see a few with dedicated heat boxes for the defrost. Check out www.robbinswings.com
Flew this morning at 18 degrees and nice and cozy.

[Battson]

I have been camping overnight and had a fogged windscreen in the mornings, but defrost was never necessary. The leakage around the wind shield means that once you are flying, things clear up.

Clearing it in the mornings can be a chore, but that goes with all aircraft. They like to re-fog on both sides of the glass until you're flying. I have never needed defrost in-flight or even come close.

This winter we did a few long cross country flights at high altitude, above 10,000ft. Temps down to -18C (0F). One cabin heater was NOT enough, nor anywhere close to enough. The flow and temperature was certainly enough, the leakage out / in at the doors overwhelms the heater. The back seats are much colder than the front too, for this reason. While we were temperate in the front, with the best puffers and gloves at times, drinks in the back froze around the edges.

With one heat muff on the exhaust, and one heater valve, temps around freezing are fine. The heater keeps the plane warm enough. I find I want the heater once the OAT hits single figures (degrees Celsius), or below about 50F. Much below freezing and things slowly start to get colder as time goes by.

I used the Vans box and muff, but I don't think the brand of box is the big deciding factor, more the leakage from the cabin, number of muffs / effectiveness of heat transfer.

[bearhawk2015]

I used a cabin heat box from aircraft spruce, works good, for heat I have 2 heat muffs hooked together and it's kept me warm down to -10f, for def I stole an idea from another bhawk and put 2 computer fans in the instrument panel that blow up on the windshield, so far it's working to keep the windshield defrosted

[Zzz]

Right, that's how I've seen most defrosters set up. I've also see a few with dedicated heat boxes for the defrost. Check out www.robbinswings.com
Flew this morning at 18 degrees and nice and cozy.

Thanks Dave, looks like good stuff. Pretty cheap too.

[Zzz]

Any advantage of stainless over alodined aluminum?

http://www.robbinswings.com/Cabin_Heat_Box.htm

vs

https://www.aircraftspruce.com/catalog/eppages/heaterbox1.php

[bestbearhawk1231]

If you end up with an engine fire I would prefer the stainless box rather than the aluminum. I watched a video a few years ago that simulated an engine fire with an aluminum box, it was amazing how quickly it melted away. I don't remember where I saw the video though. Something to think about although I hope I never have to deal with that situation.

[Battson]

If you end up with an engine fire I would prefer the stainless box rather than the aluminum. I watched a video a few years ago that simulated an engine fire with an aluminum box, it was amazing how quickly it melted away. I don't remember where I saw the video though. Something to think about although I hope I never have to deal with that situation.

That is the general wisdom, stainless will hold out longer during an uncontrolled engine fire being directly fuelled by AVGAS.

I think the Vans box I used is alloy though, I don't stay up at night worrying about it, although it's probably not ideal.

[dedgemon]

As one of the token RV guys here, I can say that the Vans valves work fine. I'm sure you can spend more and get the stainless ones and hey will work fine also. Your choice of course. The more important thing is to have enough heat muff to actually make some heat. The Vans muffs are small. Using one on my 9 wawn't enough most of the time. On my 8 I put two in series and they work GREAT.

[aerolite]

In Canada we are mandated to use SS heater box's.
The small heat muffs that just wrap around the pipe are not very good, and like dedgemon said above, he had to put two in series to work. If you are going to be flying in the cold a lot, nothing beats a proper muffler with a heat muff around it. They give off way more heat. The one's Vetterman makes for his systems are great, you get really good heat and about 6db less noise as well.

[svyolo]

I was looking at the RV-10 baffle kit and the FWF documentation. The baffle kit only shows one 2" flange behind the #5 cylinder. Do you feed both heat muffs (I have two) with one flange? There is another flange on the intake in front of #1. It's purpose I do not see listed on the baffle plans.

[Nev]

My baffle kit fed a second heat box from the #2 air intake ramp. I modified it and located it beside the other one on the #5 cylinder baffle due to space contraints.

[svyolo]

I as thinking of doing the same, or use a single 2.5" flange, and a Y to two 2" ones closer to the exhaust.